The other Ruby librarys that do parallel execution all support one primary use case - crunching through a large queue of small tasks as quickly and efficiently as possible. This library primarily supports the use case of needing to run a few larger tasks in parallel and managing the stdout to make it easy to understand which processes are logging what. This library was created to be used by the Beaker test framework to enable parallel execution of some of the framework's tasks, and allow people within thier tests to execute code in parallel when wanted. This solution does not check to see how many processors you have, it just forks as many processes as you ask for. That means that it will handle a handful of parallel processes well, but could definitely overload your system with ruby processes if you try to spin up a LOT of processes. If you're looking for something simple and light-weight and on either linux or mac (forking processes is not supported on Windows), then this solution could be what you want.